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Structure of Spoken Language

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1 Structure of Spoken Language
CS 551/651: Structure of Spoken Language Lecture 3: Phonetic Symbols and Physiology of Speech Production John-Paul Hosom Fall 2010

2 Phonetic Symbols: the IPA The International Phonetic Alphabet (IPA)
(reproduced compliments of the International Phonetic Association, Department of Linguistics, University of Victoria, Victoria, British Columbia, Canada)

3 Phonetic Symbols: the IPA

4 Phonetic Symbols: the IPA
Produced With tip of tongue, e.g. Spanish /r/ Tongue tip or blade touching upper lip

5 Phonetic Symbols: the IPA
Other IPA symbols…

6 Phonetic Symbols: the IPA

7 Phonetic Symbols: Worldbet
An ASCII representation of IPA, developed by Hieronymous (AT&T)

8 Phonetic Symbols: ARPAbet, TIMITbet, OGIbet
ASCII representation of English used in TIMIT corpus.

9 Phonetic Symbols: SAMPA
An ASCII representation for multiple (European) languages

10 Acoustic Phonetics: Anatomy
nasal tract (hard) palate velic port oral tract alveolar ridge velum (soft palate) lips tongue teeth pharynx glottis (vocal folds and space between vocal cords) tongue tip vocal folds (larynx) = vocal cords The Speech Production Apparatus (from Olive, p. 23)

11 Acoustic Phonetics: Anatomy
Breathing and Speech (from Daniloff, chapter 5): Duration of expiration in soft speech is 2.4 to 3.5 seconds; maximum value (singers, orators) is 15 to 20 seconds without distress. Louder voice requires inhaling more deeply after expiration; also deeper inhalation if followed by longer speech. More intense voicing requires greater lung pressure. Lung pressure relatively constant throughout an utterance. Emphasis in speech: greater tenseness in vocal folds yielding higher F0; greater lung pressure increases airflow (energy).

12 Acoustic Phonetics: Anatomy
the false vocal folds narrow the glottis during swallowing, preventing pieces of food from getting into the trachea.

13 Acoustic Phonetics: Anatomy
Phonation (from Daniloff, chapter 6): Phonation is “conversion of potential energy of compressed air into kinetic energy of acoustic vibration.” For voiced speech: 1. Buildup of Pressure: air pressure from the lungs pushes against closed vocal folds so that Psubglottal > Poral; buildup continues until until Psubglottal – Poral > elastic recoil force of vocal folds 2. Release: vocal folds forced open by pressure difference; burst of compressed air hits air in vocal tract, causing acoustic shock wave moving along vocal tract

14 Acoustic Phonetics: Anatomy
Phonation 3. Closure of Vocal Folds, two factors: (a) force of elastic recoil in vocal folds Vocal folds have elastic or recoil force proportional to the degree of change from the resting position. (b) Bernoulli Effect (i) energy at location of vocal folds is conserved: E = KE + PE (ii) increase in KE causes decrease in PE (iii) PE corresponds to pressure of air (iv) drop in pressure causes walls of glottis to be drawn closer together Summary: air burst causes high rate of airflow, causes drop in pressure, causes folds to be pulled together

15 Acoustic Phonetics: Anatomy
Implications: vocal folds do not open and close because of separate muscle movements 2. opening and closing is automatic as long as the resting position of the vocal folds is (near) closure, and there is sufficient pressure buildup below vocal folds 3. Factors governing vocal fold vibration: (a) position of vocal folds (degree of closeness between folds) (b) elasticity of vocal folds, depending on position and degree of tension (c) degree of pressure drop across vocal folds

16 Acoustic Phonetics: Anatomy
Types of phonation (from Daniloff, p. 194) quiet breathing forced inhalation normal phonation whisper

17 Acoustic Phonetics: Anatomy
The cycle of glottal vibration (from Daniloff, p. 171) 1. folds at rest 2. muscle contraction 5. “explosion” open 6. acoustic shockwave 3. increase in pressure 4. forcing folds apart 7. rebound toward closure 8. folds close, goto step (3)

18 Acoustic Phonetics: Anatomy
The cycle of glottal vibration (from Pickett, p. 50) opening to closure, 2.4 to 4.5 msec closure to opening, 0 to 2.1 msec (F0 = 222 Hz)

19 Acoustic Phonetics: Anatomy
Types of phonation (from Daniloff, p. 174) voiceless, whisper, breathy voiced, creak, glottal stop

20 Acoustic Phonetics: Anatomy
Some cool (gross?) videos: Video of fiberoptic stroboscopy exam: (ignore the background music!) And here’s another video from showing the vibration of the vocal folds as a person’s pitch increases:

21 Acoustic Phonetics: Anatomy
The effects of nasalization on vowels (from Pickett, p. 71) Figure An example of the effects of vowel nasalization on the vowel spectrum. The spectrum envelopes of a normal [a] and a heavily nasalized [a] were plotted… The first three formants are labeled in the normal vowel. In the nasalized vowel, there are three local reductions in spectrum level, indicated by “z’s”; these are the result of the addition of anti-resonant zeros to the vocal tract response, due to a wide-open velar port.

22 Acoustic Phonetics: Anatomy
The effects of nasalization on vowels (from Pickett, p. 71) Coupling of the oral and nasal tract introduces pole-zero pairs (resonances & anti-resonances, occurring in pairs) in the spectrum. The amount of coupling affects the spacing between each pole and its corresponding zero, as well as their frequency locations. The presence of a pole-zero pair increases the apparent bandwidth of the neighboring formants. The presence of spectral zero below F1 tends to make the location of F1 appear slightly higher ( Hz) than it normally would If the zero is higher in frequency than its corresponding pole, the net effect is to reduce the amplitude of higher frequencies

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